The way it is angled, the outflowing air sucks a bit of air from the front wing creating extra downforce, and the exhaust flow/pressure coming out of the pipes helps the underfloor + rear downforce :)

Ingenious, and no doubt will be banned after countless complaints or deemed legal and copied asap. Hope it works out for them – kubica deserves a title! This is the kind of innovation that is needed in F1, so i hope it is allowed to stay